import sys
def input(): return sys.stdin.readline().rstrip()
def main():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No")

if __name__=='__main__':
    main() import sys sys def input(): return sys.stdin.readline().rstrip() input def main():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No") main x = int(input()) x int(input()) int input() input if x >= 30:
        print("Yes")
    else:
        print("No") x >= 30 x 30 print("Yes") print "Yes" print("No") print "No" if __name__=='__main__':
    main() __name__=='__main__' __name__ '__main__' main() main def main():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No") def main():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No") main def input(): return sys.stdin.readline().rstrip() def input(): return sys.stdin.readline().rstrip() input
import sys
def input(): return sys.stdin.readline().rstrip()
def main():
    x = int(input())
    if x >= 30:
        print("Yes")
    else:
        print("No")

if __name__=='__main__':
    main()